The invention relates to an electrical test device, in particular for the purpose of testing wafers, having a contact head, which is associated with the test object and is provided with pin-shaped contact elements forming a contact pin arrangement, and having an electrical connection apparatus, which has contact faces which are in touching contact with the ends of the contact elements which face away from the test object.
Electrical test devices of the type mentioned initially serve the purpose of making electrical contact with a test object in order to test its functionality. The electrical test device produces electrical connections to the test object, i.e., on the one hand, it makes contact with electrical connections of the test object, and, on the other hand, makes available electrical contacts which are connected to a test system which supplies electrical signals to the test object via the test device in order to carry out, for functional testing purposes, for example, resistance measurements and current and voltage measurements etc. Since the electrical test object is often an extremely small electronic component, for example a wafer, from which electronic components are produced, the pin-shaped contact elements of the contact head have very small dimensions. In order to make possible a connection to the mentioned test system, the contact elements of the testing head are in touching contact with a connection apparatus which carries out a conversion to a greater contact spacing and, in this regard, makes possible connection of electrical connecting cables which lead to the test system. Since different room temperatures may be present during testing and the testing is preferably also carried out at different test object temperatures in order to be able to test its operation within a specific temperature range as well, in the case of the known electrical test devices there is the risk that, owing to thermally induced changes in the length, contact between the contact elements and the associated contact faces of the connection apparatus is not always ensured in a fault-free manner owing to positional errors brought about. These shifts in position result from different coefficients of thermal expansion of the materials used, it being necessary for design reasons to use specific materials such that the abovementioned problem cannot be resolved by selecting the same material for the contact head and the connection apparatus. Different degrees of heating of individual parts also lead to shifts in position.